Keyboard, being the most common input interface available on the market, is vastly used in many electric devices, such as computers, person digital assistances, cellular phones, and so on. With the advance of technology, keyboard that can emit light are gradually becoming the mainstream product of keyboard manufacturing industry since it is well adapted to be used in an environment that is not so well illuminated. Such light-emitting keyboards are especially suitable to be applied in notebook computers as the notebook computer, being designed to be carried around and used in all kinds of environments possible, that are equipped with light-emitting keyboards can operate easily under any illumination conditions. In addition, for meeting the growing personalization requirements of today's consumers, light-emitting keyboards can be designed with a hint of amusement for enabling the same to operate with dashing visual effects.
Please refer to FIG. 1A and FIG. 1B, which is a cross sectional view of a conventional light-emitting keyboard. As shown in FIG. 1A and FIG. 1B, the conventional light-emitting keyboard 100 is comprised of: a light guide plate 110, a light emitting diode (LED) 120 and a frame 130, in which the light guide plate 110 is configured with a light entrance surface 112 and a light emitting surface 114 whereas the light emitting surface 114 is constructed next to the light entrance surface 112; and the LED 120 is disposed at a position next to the light entrance surface 112 while the frame 130 is disposed on the light emitting surface 114 of the light guide plate 110.
Moreover, for discharging any liquid accidentally permeating into the light-emitting keyboard 100, there is a via hole 116 formed on the light guide plate 110 that is provided for guiding the liquid to flow out of the light emitting keyboard 100 therefrom. With the aforesaid structure, light emitted from the LED 120 will enter the light guide plate 110 through the light entrance surface 112 and leave the same through the light emitting surface 114 and then enter the frame 130 for enabling the frame to radiate light.
Generally, by properly arranging a plurality of reflection points on the light guide plate 110, the frame will be enabled to radiate light evenly. However, it is certain that there will be a portion of light passing through the via hole 116 and thus entering into the frame 130 which is going to cause the area of the frame 130 that is located corresponding to the via hole 116 to be brighter than other areas. Therefore, the brightness of the frame 130 is not evenly distributed. As it is obvious to users that the area of the frame 130 located corresponding to the via hole 116 is brighter, it is easy to raise a question regarding to the quality of the light-emitting keyboard 100.
Moreover, being one of the components used in notebook computers, the light-emitting keyboard 100 is usually being received inside the housing of the notebook computer while coupled to the monitor of the same. Therefore, if the monitor is being received inside a black or dark colored casing, or simply the housing of the notebook computer is black or dark colored, the portion of the frame 130 of the light-emitting keyboard that is neighboring to the monitoring casing will appear to be much brighter. Such huge brightness difference is going to cause incompatibility between the light-emitting keyboard 100 and the computer housing that is not aesthetically pleasing.
Please refer to FIG. 2A and FIG. 2B, which is a cross sectional view of another conventional light-emitting keyboard. As shown in FIG. 2A and FIG. 2B, the conventional light-emitting keyboard 200 is comprised of: a light guide plate 110, two light emitting diodes 220a, 220b and a frame 230, in which the light guide plate 210 is configured with two light entrance surfaces 212a, 212b and a light emitting surface 214 whereas the light emitting surface 214 is constructed next to the two light entrance surfaces 212a, 212b; and the two LEDs 220a, 22b are disposed at positions respectively corresponding to the two light entrance surfaces 212a, 212b while the frame 130 is disposed on the light emitting surface 214.
It is noted that the two LEDs 220a, 220b are designed to emit two beams of different colors, and correspondingly, the light emitting surface 214 of the light guide plate 210 is divided into a first light-emitting zone 214a and a second light-emitting zone 214b for emitting the two beams in respective. Thereby, the portion of the frame 230 corresponding to the first light-emitting zone 214a will display a lighting/coloring effect different from that of the portion of the frame 230 corresponding to the second light-emitting zone 214b. 
However, it is inevitably that a mixing-light effect will be caused at the interface between the first light-emitting zone 214a and the second light-emitting zone 214b. Accordingly, the boundary separating the two light-emitting zones 214a and 214b is not apparent or even appears to be smeared that it is easy to raise a question regarding to the quality of the light-emitting keyboard 200.
Please refer to FIG. 2C, which is a cross sectional view of yet another conventional light-emitting keyboard. In the embodiment shown in FIG. 2C, the light-emitting keyboard 200a is constructed similar to that shown in FIG. 2A, but is different in that: the light-emitting keyboard 200a is further configured with a shielding layer 240 at a position between the light-emitting surface 214 of the light guide plate 210 and the frame 230. It is noted that the shielding layer 240 can be a transparent film being divided into a plurality of blocks of different colors. In this embodiment, the shielding layer 240 is divided into a first shielding zone 240a and a second shielding zone 240b while enabling the two shielding zones 240a, 240b to be located respectively at positions corresponding to the first and the second light-emitting zones 214a, 214b. Moreover, as the two LEDs 220a and 220b are white light LEDs, and the first and the second shielding zones 240a, 240b are coated with inks of different colors for allowing only lights of corresponding colors to pass therethrough in respective, the portion of the frame 230 corresponding to the first light-emitting zone 214a will display a lighting/coloring effect different from that of the portion of the frame 230 corresponding to the second light-emitting zone 214b. However, it is also inevitably that a mixing-light effect will be caused at the interface between the first light-emitting zone 214a and the second light-emitting zone 214b. Accordingly, the boundary separating the two light-emitting zones 214a and 214b is not apparent or even appears to be smeared that it is easy to raise a question regarding to the quality of the light-emitting keyboard 200a. 